The half life of many xenobiotics is dramatically shortened by conjugation of the xenobiotic with a substance which greatly increases the water solubility of the conjugate. Conjugation frequently occurs secondarily to the primary metabolism of the xenobiotic in the liver. Unfortunately these conjugates are quite easily hydrolyzed, both nonenzymically and enzymically, especially in the intestinal tract. Therefore intestinal enzymes for the conjugation, or reconjugation, of xenobiotics plays an important role in the excretion of xenobiotics. Because the activity of these enzymes is related to the structure of the membrane in which they are found, they are extremely difficult to study or even quantitate. We do not know how many enzymes there are, what their substrate specificity may be, or even how much of their activity can be expressed in the native membrane. The objectives of this research program are to purify one enzyme for the conjugation of xenobiotics from the intestine, to study its physical properties, to characterize its interaction with the membrane and ultimately to determine its role in the metabolism of xenobiotics. Most of these objectives must await purification of the enzyme. Therefore this continues to be the primary objective of the proposed research. Other projects, such as substrate specificity and the effects of detergents, are studied as the enzyme is being purified.